Protective system for electrical machinery



April 29, 1924. 1,492,022 A c. c. EDDY PROTECTIVE SYSTEM FOR ELECTRICALMACHINERY Filed June 9, 1919 I Patented Apr. 29, 1924.

UNITED STATES 1,492,022 PATENT OFFICE.

CECIL CLEMENT EDDY, or LOS ANGELES,

CALIFORNIA, ASSIGNOR 0F ONE-HALF TO FRITZ W. FALCK, 0'! LOS ANGELES,CALIFORNIA.

PROTECTIVE SYSTEM FOR ELECTRICAL MACHINERY.

' Application filed .Tune 9,

To all whom it may concern:

Be it known that I, CEorL CLEMENT EDDY, a citizen of the United States,residing at Los Angeles, in the county of Los Angeles, State ofCalifornia, have invented new and useful Improvements in ProtectiveSystems for Electrical Machinery, of which the following is aspecification.

' This invention relates to protective systems or devices for electricalmachinery, relating generally to protection of dynamo or motormachinery, or such machinery as rotary converters, etc..in fact to allelectrical machinery in which there is rotor and stator arrangement. Insuch machinery there is-usually a very small clearance between the rotorand stator, and the small wearing of thebearing very often allows therotor to come into physical contact with the stator, immediatelydeveloping intense heat which will usually cause great damage to themachine, burning out the coils and doing other damage. It is an objectof this invention to prevent such damage to such machinery. I

In providing such a system I prefer to make my system applicable ofcourse to such installations as are now in common use; and so, withoutlimiting myself thereto, I show my system in connection with the usualswitch control system for such electrical machinery. For instance, asapplied to a motor installation, I arrange my safety system in such amanner as to co-opcrate with the usual form of control switc forallowing that control switch to shut off the current to the motor incase the rotor comes into contact with the stator. From a specificdescription of a typical form of such an installation, it will bereadily apparent to those skilled in the art how my system may beapplied to other installations.

Furthermore, there are a great many ways in which m system may .beinitially set in actuation; t at is, there may be a great many differentforms of devices which may be set in the motor or dynamo or other1nachine for the purpose of causing stoppage of the machine, in case therotor comes into contact with the stator; but I herein show and describespecifically one preferred simple form of such device. This preferredform embodies a fusible current conductor which may be melted by theheat of friction immediately when the rotor comes in contact with thestator; and the break in circuit 1919. Serial No. 302,392.

thus made causes the actuation of the main supply switch to cut oficurrent to the motor.

With these preliminary observations in mind, the invention will now bebest understood from the following detailed and specific description ofa preferred form thereof, reference for this purpose being bad to theaccompanying drawings, in which Fig. 1 is a diagram showing the generalarrangement of my system; Fig. 2 is a diagram showing the generalelectrical connections of the control devices which are placed in themachine itself; Fig. .3 is an enlarged plan showing the pole faces ofthe stator as equipped with my devices; Fig. 4 is a plan of one of thedevices itself; and Fig. 5 is an enlarged section showing the placementof the control elements or devices in the stator.

Stators are usually provided with winding slots 10 in which the coils 11are placed; and over these coils slot sticks 12 of fibre or the like areusually placed for the purpose of protecting the windings. In apreferred installation of my system I simply remove some of these slotsticks and insert my special slot sticks. My special slot sticks may bemade as is best shown in Figs. 4 and stance, a fusible conductor wire 17being threaded back and forth through holes 18 in the strip 16. Thesewires come out of my special slot stick as shown at 17; and the wires ofadjacent slot sticks may be connected together, so that the conductorsof all these special slot sticks are in series; and then two connectingwires 20' and 21 may be run from the slot stick conductors thusconnected in series. My special slot sticks, which I enerally indicateby the numeral 12*, may e placed in any desired osition in the stator.Where the wear on t e rotor bearings is downward, the slot sticks willbe placed in the lower part of the stator; or where the wear on thebearings is in some other direction, due for instance to the pull of abelt on the rotor shaft, the slot sticks may be placed inany part orparts of the stator with which the rotor is liable to come into contact.

It will be readily understood that if the rotor comes into contact withthe stator at any point, heat is immediately generated. In fact, thisheat is usually so intense that the coils are immediately burned out.Now

the fusible wire conductors 17 are made large enough so that they willpass the current which must be normally passed throu h them (for thepurpose hereinafter escribed) without heating them to the melting point;but they are preferably made of a low melting material, so thatimmediately any heat is generated by contact of the rotor with thestator, these wires will immediatel melt and will break the electriccircuit. X melting of any one-of the conductor wires 17 at any one pointwill of course break the circuit, as all these wires are in series.

At S I show a typical switch of a motor installation, cont-rolling themain lead wires W which supply current to the motor M.

Such a switch as shown at S may be of the type which, when thrown overto its position, in which it is supplying full current to the motor, isheld in that position by an electro-magnetically actuated catch; andupon release of the catch a spring will throw the switch back to its offosition. The catch which holds the switc in its on position is acuatedby a ma et orsolenoid 30. As long as this soleno1d is energized, thenthe switch is held in its on posltion; but de-energization of thissolenoid will im mediately allow the switch to 0 back to its offposition. This is a usua and ordinary construction and does not need tobe here explained, in detail. The electromagnet 30 is usually connectedby wires into the main supply circuit; so that if for any reason thecurrent in the main supply circuit fails, the control switch will bethrown to its off position. I connect my s ecial stator stick 12 intothis circuit, as wi now be described. For instance, one side of theelectro-magnet 30 may be connected by wires 31 with one of the feedwires W, and from the other side of the electro-magnet a wire 32 maylead to the wire 20 hereinbefore described. The wire 21 hereinbeforedescribed may be connected with a wire 33 which connects with anotherone of the feed wires W. In the wires 31 and 33 there may be a smallmanually o erable switch 34; and in the wires 32 an 33 there may be afuse block 35 to prevent the passa e of such a current as might fuse thecon uctor wires 17 of the slot sticks 12. It will be apparent withoutfurther detailed description, that a melting of any one of theconductors 17 in any one of the slot sticks will break the circuitthrough the switch magnet 30 and will allow the switch to immediately g0t0] its off position, cutting otf the current to the motor. While thecircuit is in this condition, it will be impossible to keep the motorrunning, because the magnet 30 cannot be energized, and hold the switchclosed, until the circuit is repaired. Repair is easily efi'ected byremoving the injured slot stick and inserting a new one, or by replacingthe melted wire in the slot stick.

At the same time that the switch S is operated by breaking of thecircuit through the magnet 30, a buzzer or other signal may be operatedto give a signal to the person in charge. For instance, I ma use a highresistance buzzer B connecte by wires 40 across the two wires 32 and 33.The resistance of buzzer B is high enon h, and the resistance of theslot stick wires ow enou h, that, while the circuit is normally virtufilshorted through the slot stick wires, buzzer B will not be operated. Butimmediately the circuit through the slot stick wires is broken, then thebuzzer B will take current and will be operated; but the resistance inthe buzzer B is so high that it will not pass current enough to energizemagnet 30 sufliciently to cause it to hold the switch S in its onposition.

Having now described a specific and preferred form of my protectivesystem, it will be apparent to those skilled in the art how the systemmay be modified or varied to apply it to the different installations,and how the elements or devices of the system may be modified or variedto effect the same results in such various installations withoutdepartin from the sec e of my invention. In fact,% do not consi er myinvention as at all limited to the particular things herein set forth,and I have made this specific description not at all for the urpose oflimiting my invention thereto, but for the purpose of clearly explainingone practical orm which my invention ma take as a plied to one kind ofmachine of t e general class to which my invention is applicable.

Having thus described a preferred form of my invention, I claim:

1. n a device of the character described, a slot stick embodying a bodyof electrical insulating material and a fusible wire extending throughsaid body.

2. In a device of the character described,

a slot stick, embodying a central sheet of electrical insulatingmaterial, a fusible wire threaded through said sheet, and side sheets ofelectrical insulating material-one on each side of the central sheet andthe fusible mm.

3. In a device of the character described,

an elongate bod of insulating material like, and a fusible conductorcontained with- 10 adapted to be p aced in a slot in one of therelative] rotating parts of a motor or the like, an a fusible conductorextending through said body.

4. In a device of the character described, an elongate body ofinsulating material adapted to be placed in a slot in one of therelatively rotating parts of a motor or the in and covered by the body.

In witness that I claim the foregoin I have hereunto subscribed my nametis 7 26th day of May, 1919.

CECIL CLEMENT EDDY. Witnesses VIRGINIA I. BERINGER, W. H. MAXWELL.

